1. Field of the Invention
This invention relates to storable polyol premixtures for making polymeric foams and more particularly relates to such premixtures for the preparation of polyurethane and polyisocyanurate foams.
2. Description of the Prior Art
The use of foamed polyurethanes and polyisocyanurates as thermal insulating materials, packaging foams, etc. is widespread. It is common practice in the manufacture of such cellular foam materials to mix two preformulated components, commonly called the A-component and the B-component. Typically, the A-component contains the isocyanate compound that must be reacted with the constituents of the B-component to form the foam, and the B-component commonly contains the balance of the foam ingredients, namely, polyol, blowing agent, surfactant and catalyst.
An inexpensive source of polyols for foam insulation systems is now available through the use of waste stream aromatic polyesters and aromatic polyesters reclaimed from bottles, film scrap, etc. Unfortunately, these polyols suffer the disadvantage of incompatibility with the fluorocarbon blowing agents commonly employed in the production of the foams. While the problem can be partially overcome by combining the aromatic polyester polyols with various polyol types conventionally used in foam production, this approach detracts from the desirable foam properties, such as good flame resistance, and cost reduction associated with use of the aromatic polyols. Another approach is to add compatibilizing agents as fluorocarbon solubility aids. The latter approach is exemplified in U.S. Pat. No. 4,529,744, wherein a dual compatibilizer system is needed to provide the disclosed miscible blends of polyol and blowing agent.
Therefore, there still is a need for simple and inexpensive ways of promoting the compatibility of polyols, especially aromatic polyester polyols, with fluorocarbon blowing agents and thereby providing homogeneous and storable polyol blends for use in manufacturing foams of good quality and low cost.